In the fourth season episode "Tunguska," the X-Files mythology kicked into high gear, introducing the now-infamous extraterrestrial "Black Oil" that infected and controlled human beings. As it turns out, the discovery of the Black Oil in a meteorite was based on a real-life incident: the claims of alien life found in the Allan Hills 84001 meteorite.

In 1984, a team of U.S. meteorite hunters discovered a rock in Allan Hills, Antarctica that was found to be of Martian origin. It is the oldest meteorite ever discovered from Mars, and is thought to have crystallized from molten rock 4.091 billion years ago, back when Mars had abundant liquid water. Within the meteorite, NASA scientists found evidence of polycyclic aromatic hydrocarbons (PAHs), a type of organic molecule that is released by nanobacteria found on Earth, leading them to believe that organisms may have once lived inside the rock. They also found magnetite and carbonate, which are often found with the fossils of nanobacteria, leading NASA to conclude that the rock contained fossils of alien life.

In the episode, Mulder and Scully work with a scientist named Dr. Sacks who claims he has discovered a meteorite containing PAHs, which gets him all excited that he's discovered extraterrestrial life. In his scenes with Mulder and Scully, the characters not only imitate the discovery of the Allan Hills meteorite, they reference it:

"Dr. Sacks's excitement in finding that the meteorite contains PAHs is therefore understandable- he believes that this meteorite also contains signs of ancient extraterrestrial life," Simon writes. "But PAHs by themselves are just one piece of the puzzle. Dr. Sacks tells Mulder and Scully that he wants to search for microfossils in the rock's interior. Scully correctly reminds Dr. Sacks that many scientists doubt that ALH84001 contains any fossils of ancient Martian life."

There have been dissenting voices claiming that the Allan Hills meteorite does not contain extraterrestrial life ever since the discovery was made, and those voices have grown louder over the years. First, the examination of the rock required an instrument that coats it with metal, which some scientists argue may have actually created the tiny objects that look like fossils (although further studies have discredited these concerns somewhat). Further, while nanobacteria certainly exist, many scientists claim they are too small to be truly alive. At one-thousandth the volume of a normal bacteria, it would only have room for a few ribosomes, a few hundred proteins, and eight genes, while the consensus is that at least 250 genes are necessary for replication, a common criterium for life.

"For nanobacteria to be real cells, and not artifacts of the investigation methods, then they must have a biochemistry completely at odds with the biochemistry of all other organisms on Earth. While this may be a common occurrence in science fiction, it is much less likely to be true in real life."

So the claims that we found extraterrestrial life have been somewhat discredited, but not completely disproven. Simon wrote this book in 2001, and as recently as 2009, NASA's David S. McKay, who was quoted in the original article, teamed up with several other scientists to publish research that the biogenic theory was still the most likely explanation. So who knows?